Single polar telegraph circuits



- I E. F. WATSON SINGLE- POLAR TELEGRAPH CIRCUITS INVENTOR my BY 7 ATTORNEY SSQ s p ia oriflinal'Filed Nov. 21, 1921 Patented June 16, 1925.

UNITED STATES P T OFFICEQ EDWARD r. wA'rsoii, or YonKnas, NEW YORK, ASSIGNOR TO AMERICANTELEPHONE AND TELEGRAPH COMPANY, A conronnrron on NEW YORK.

SINGLE POLAR TELEGRAPII CIRCUITS.

Application filed Nove mber 21, 1921, Serial No. 516,871 Renewed October 22, 1924.

To all whom it may concern: 7

Be'it known that I, EDWARD F. WATsoN, residing at Yonkers, in the county of lVestchester and State of New York, have invented certain Improvements in Single Polar Telegraph Circuits, of which the following is a specification.

This invention relates to telegraph circuits and more particularly to the type of telegraph circuit known as single Morse circuits in which signals are transmitted in but one direction over thesame line at one timeyalthough the system is so arranged that signals may be transmitted in either direction. a

One of the objects of the invention is to producea signaling system inwhich signals may be transmitted n ither direction over a line wire without balancing the wire.

Another object, of the invention is to produce a signaling system in which signals consisting of positive and negative impulses may be transmitted in either direction over a line wire without balancing the wire.

Another object of this invention is to produce a system in which the line will be switched into connection with the transmitting apparatus at one end and the receiving apparatus at the other end, but, under suitable conditions, may be switched into connection with the receiving apparatus at the first mentioned end and into con nection w th the transmitting apparatus at the other endii'or transmitting signals in the reverse direction. i

Another object of the invention is to provide a system in which the stations at each end of the line are provided with a transmitting and a receiving apparatus, the transmitting apparatus at one station being connected with the line and the receiving apparatus at the other station being connected with the line when signals are transmitted in one direction, the system being so arranged that, by transmitting a break signal from the station which is receiving, the connections may be interchanged to connect the transmitting apparatus with the line at the receiving station and the receivingapparatus, with the line at the transi'nitting stationywhereby signals may be transmitted in the opposite direction.

tics above referred toin which the switching apparatus for determining whether the line will be connected to the transmitting or to the receiving apparatus ata given station will be under the control of a relay responsive only to abnormal current conditions in theline. i

The above objects,

as well other objects of the invention,

will be clear from the fol:-

connection with the accompanying drawing, Figs. 1 and 2 of which illustrate two forms of telegraph systems embodying the principle of the invention.

lowing description thereof when read in l Referring to Fig.1, ML designates a main transmission line for a telegraph circuit terminating at opposite ends at two stations indicated as A and B respectively. At station A alocal loop L extends to a subscribers, station at which suitable transmitting and receiving apparatus may be provided, for example, the loop L is illustrated as including a schematically -indicated transmitting distributor TD of a printing telegraph set and a home recording relay HRR of such a set.

The loop L at station A is balanced. by means of=a balancing circuit or a resistance N, and windings of a polar pole changing relay PC and a polar break release relay BRR are included in the loop L and balancing circuit N. At the junction point between the loop Land the balancing circuit N a connection extends to the armature of a polar receiving relay RR, which relay may, under certain conditions, be associated with the main line ML for transmitting signals to the loop.

A transfer relay TB is so arranged that it may switch the main line ML either into connection withthe receiving relay RR or into connection with the transmitting ap paratus controlled by the armature of the pole changer PC. The connection fromthe main line ML to the armature 'of the pole changer PC includes the winding of a break relay BR. The break relay BB is a marginal neutral relay so designed that it will be unresponsive to positive or negative currents transmitted over the line in connection with ordinary signaling, but will be, responsive to, a current of greater ampli; hide transmitted, over the lineas the result of a break signal. The transfer relay TR has an initial energizing circuit. controlled by the contact of the break relay BR and has a locking circuit controlled by its locking contact and by a contact of the break release relay ERR. This circuit may also include- 'a break release key BRK for performing the functions of a break release relay manually, when desired.

As illustrated, the apparatus at station E is somewhat different from that at station A, as it is so arranged that the terminal apparatus and the printing apparatus may both be installed at the same station instead cf have the printer located at a somewhat distant point from the terminal apparatus associated with the terminal station through a 1001) such as the loop L at station A. In this case the pole changing apparatus coinpris'es two polar relays PC and PC, each having two windings so arranged that one Winding of each relay is included serially in circuit with a low resistance, the other windings of the relays being" in a high resistance circuit. The forward circuit includes the break key BK, the transmitting distributor TD and the home recording relay HRH. The windings of the pole changing relays in the two circuits tend to shift the armatures in opposite directions, but as the windings in the low resistance circuit receive the most current, said windings will determine the positions of the armatures nformally. hen the low resistance circuit is opened either by the break key BK or the transmitting distributor TD, the armatures will be shifted under the control of the windings in the high resistance circuit.

In order to "supply signaling current, a motor generator G may be provided, and the circuit of this generator is so arranged that the armatures of the pole changers PC and PG determine the polarity of the current supplied from the motor generator. A connection extends from this generator through a break relay BR, similar in all respects to the break relay at station A, to the back contact of the transfer relay TR. The transfer relay TR performs the same functions as the transfer relay at station A and is initially controlled by the break relay BR. Its locking circuit, however, is arranged to be opened by the break key BK, as no release relay is provided. When the transfer relay is locked up, a re-v ceiving relay RR is connected to the main line, but when the transfer relay is deener= gized, the main line is connected to the motor generator set over the contacts of the pole changers, The receiving relay HR is arranged to establish connection over its marking contact to the selecting circuit on the receiving distributor face of the receiv ing printer (not shown) Qver its spacing contact it controls the connection to the start circuit of the receiving distributor, so that the first spacing impulse of a group will release thercceiving distributor in a wellknown manner. The home recording relay HRR is arranged, so that when it is energized, as is the case during the transmission of marking signals, it will close the circuit over the marking contact of the receiving relay RH, and when it is deenergized during: the transmission of spacing signals, it may independently control the starting cir cuit of the receiving distributor. In this manner the receiving relay RR will operate the local printer when the station is receiving signals, and when the station is sending signals the home recording relay will operate the local printer independently of the receiving relay.

Further details of the apparatus will now be clear from a description of the operation, which is as follows:

As illustrated, the apparatus at stations A and B is in condition for transmitting from the former to the latter. The transfer relay TR at station B is locked up and connects the line to the receiving relay RR. At station A the transfer relay TB is deenergized, so that the line is connected to the contact of the pole changer PC. The receiving relay HR at station A is locked up over the back contact of the transfer 103 relay TR to negative battery, so that its armature is held against its negative contact. lVhen the loop is closed, therefore, current flows from negative battery over the contact of the receiving relay RR, through the loop windings of the pole changer PC and break relay BRR, over the break key BK, through the transmitting distributor TD and through the winding of the home recording relay HRR to positive battery. Current also flows from the negative contact of the receiving relay through the balanci-ng windings of the pole changer PG and break release relay BRR through the balancing resistance N to ground. Obviously the current flowing through the loop windings of the pole changer and the break release relay is substantially twice as great as that flowing through the balancing windings owing to the fact that the positive and negative batteries are connected in series with respect to the loop circuit. The tendency of the current flowing through the balancingwindings is to shift the armature of the pole changer PG and the break release relay BRR to their upper contacts, but owing to the greater pull in the opposite direction, due

to the loop windings of said relays, the a'rmatures are held to their lower contacts, so

that negative battery is connected through the winding of the break relay BR and over the right-hand back contact of the transfer relay to the main line ML. The resultant line current flows over the front left-hand contact of the transfer relay TR at station B and through the winding of the receiving relay RR to ground. The armature of the receiving relay RR is therefore held. against its lower contact, so that a connection is completed from ground over the right-hand front contact of the home recording relay HER and over the lower contact of the receiving relay RR to the selecting circuit of the receiving distributor face (not shown). I

The conditionsjust described obtain during the transmission of marking signals. W hen a spacing signal is to be transmitted, the loop L will be opened by means of the transmitting distributor Tl.) at station A, so that no current flows through the loop windings of the pole changer PG and the break release relay BRR. The balancing windings of these relays now become effective toshift their armatures. The shifting of the armature of the break release relay ERR is without effect, as it merely opens the circuit of the transfer relay TR which is already deenergized. The armature of the pole. changer PC, however, connects positive battery to the main line ML, so that the receiving relay RR at station .B shifts-its armature to its upper contact thereby completing a circuit from ground over the right-hand front contact of home recording relay ,I-I RR andover the upper contact of the receiving relay RR to the starting circuit of the receiving distributor face. In the operation of a printer the first space signal of a group functions to release the receiving distributor of the printer in a well-known manner, and succeeding'spacing. impulses of the group are withouteffect. The succeeding marking impulses, however, complete selecting circuits ina well-known manner to deteunine the character to be printed.

If, when signals are being transmitted from station A, it is desired to t'ansmit signals from station B, thebreak key BK- .may be actuated, therebv opening the low resistance circuit through the windings of the pole changers PC and PC" and incidentally releasing the home recording relay I-IR-R and unlocking the transfer relay TR. =The deenergization of the transfer relay TR result/sin the connection of the line ML through the winding of the break relay BR to the motor generator G. The windings of the pole changers which arcinof the sending distributor cluded in the high resistance circuit at the same time become effective to shift the ar-- cuit in this condition, whenever the armature of the pole changer PC at station A rests upon its negative or marking contact in the transmission of a marking signal, the line current will be augmented from its normal value to approximately double value. The break relays BR and BR, be ing marginal, are unresponsive to the transmission or ordinary marking and spacing signals,.but as soon as'the augmented current flows, due to the lfnfeaking operation, both relays are energized. The operation of the break relay at station E has no effect, as the circuit of the transfer relay TR is held open by the break key BK. The break relay BR at station A, however, closes a circuit through the transfer relay TR over the contact of the break release relay BRR. The transfer relay TR is therefore energized, locking itself up independently of the break relay .BR and connecting the line ML at its front right-hand contact to the receiving relay RR, at the same time disconnecting the line from the contacts of the pole changerlPC thereby causing deenergiZatio-n of the break relay BR. Since a spacing or positive impulse is being transmitted from station B while the break key BK is open, the armature of the receiving relay will be shifted to its positive contact thereby short circuiting the loop L and causing current to flow through the balancing windings of the pole changer PC and the break release relay ERR in such a direction as to, hold their armatures upon their lower contacts. This prevents the armature of the break release relay from op ening the circuit of the transfer relay, which remains locked. up. i

The short-circuiting of the subscribers.

loop, when the armature of the receiving relay is connected to positive batter causes the home recording relay HRR to remain released, and this results inthe stopping TD in a manner well-known in the art. No further sending operation can take olace from station A until the break my RK at station E is released. hen the break key is released the receii 'ing relay RR at station A. willlshift its armature to its negative'contact, and current will again flow in the loop, so that the apparatus :isready to receive signals. Signals may betransmitted from station B by interrupting the low resistance circuit of the pole changers through the agency of the transmitting distributor TD, thus sending positive and negative spacing and mark ing currents from the line ML to the receiving relay RR. Each marking signal causes current to flow through the loop by shifting the armature of the receiving relay to negative battery, and each spacing signal causes a no current condition iii the loop by shifting the armature to its positive contact thereby short-circuiting the loop. During the short-circuited condition of the loop, the loop windings of the pole changer PG, the home recording relay- I-IRR and the break release relay BRR will he deenergized in the manner d- .ihed in connec-sionavith the transmission of the break signal.

In order for station A to again send signals to station B, it will be necessary to transmit a break signal from station A. This may be done by operating the break key BK in the loop L at station A, so that no current flow through the loop. As soon as a marking signal is received from station B so that the armature of the receiving relay RR is shifted to its negative contact, the pole changer PC and the break release relay BRR will shift their armatures to their upper position. The break release relay BRR opens the circuit of the transfer relay TR thereby disconnecting the line ML from the receiving relay and connecting the line to the contactsof the pole changer PC through the break relay BR. At its left-hand back contact the transfer relay TR connects'negative battery to the receiving relay RR, so that its armature is held against its negative contact. The pole changer PC at the same time connects positive battery to the line through the winding of the marginal relay BR, and since negative battery is connected to the line at the station B, an augmented current will flow on the line which 'will operate the break relays at both stations. At station A the operation of the break relay BR is ineffective, as the circuit for the transfer relay TR, through the contact of the break relay, is open at the contact of the break release relay BRR, and the transfer relay therefore remains deenergized. The operation of the break relay BR at station B closes the circuit for energizing the transfer relay TR from negative battery over the front contact of the relay BR through the winding of the transfer relay TR and over the contact of the break key BK to positive battery. The transfer relav TR is acccordingly energized and locked up over its right-hand front contact, and at its lefthand contact the transfer relay disconnects the line NIL from the generator G and connects it to the receiving relay RR.

As soon as the line is disconnected from the generator G further operations of the pole changers PO and PG under the control of the transmitter TD will be without effect so far as the transmission of signals is concerned. Moreover, since a spacing signal is being transmitted from station A as a result of break, the armature 0f the re ceiving relay RR will be shifted to its upper contact, so that the selecting circuit of the distributor will be held open at the end of the cycle thereby stopping the send ing distributor in a well-known manner. The apparatus is now again in condition for the transmission of signals from station A to station B.

It may sometimes occur that when station B has been receiving signals no more signals will be sent from the station A over the line for a period. The appa 'atus will therefore remain in the condition shown in the drawing, so that signaling can only take place from station A to station B. If, under these circumstances, the operator at sta tion B should start the transn'iitter to function, the transmitter would not transmit signals to the line, for the line would be disconnected from the transmitter over the front left-hand contact of the locked up transfer relay TR. Furthermore, there would be nothing to indicate to the operator that signals were not being transmitted. In order to prevent this possibility an additional contact may be provided for the transfer relay TR, as shown at the ex trcme right of said relay, and this contact may be included in series with the sending selection circuit of the printer, so that when it is open no signals will be sent. A failure of the apparatus to function under these circumstances will notify the operator that the break key BK should be actuated to shift the connections of the line at the terminal station.

A modified form of circuit for use at a terminal station such as that of station B of Fig. 1 is illustrated in Fig. 2. In this case the pole changer PC is simply a neutral relay serially connected in a simple series circuit including the transmitting distributor TD and the break key BK. A parallel circuit from the break key BK also extends through the transfer relay TR, which is arranged to be initially energized by the break relay BR and to be locked up through the break key BK. When the transfer relay TR is energized, the break relay BR will be open-circuited, and the receiving relay RR will be serially included between the main line ML and ground, the line connection to generator G being also open circuited at the same time. lVhen, however, the transfer relay TR is deenergized, as is the case when sending, the receiving relay RR will be serially included in a circuit over the line through the break relay BR and through the generator G to ground. By thus including the receiving relay in the circuit both for sending and receiving, the local printer may be used as a lil receiving printer when the station is re-' ceiving and as a home recording printer when the station istransmitting. The receiving relay will thus perform both the functions of the receiving relay and the home recording relay.

Further details of the apparatus will be clear from a description of the operation. Assume that station A is transmitting and station B is receiving. The transfer relay TR will be locked up over a circuit from positive battery over the break BK through the winding of the transfer relay TR and over its inner right-hand front contact to negative battery. The main line ML will be connected through the receiving relay RR directly to ground. The negative marking impulses and positive spacing impulses transmitted from the station Av will actuate the receiving relay RR to control the receiving printer in a well-known manner without in any way affecting the transmitting apparatus.

If it should be desired to transmit signals from the station B, the break key BK may be held open thereby deenergizing the pole changing relay PC and unlocking and deenergizing the transfer relay TR. The de eneii'gization of the pole changing relay shifts its contacts to reverse the terminals of the generator, so that the negative ter minal is connected to ground and the positive terminal is connected over the left-hand back contact of the transfer relay TR through the receiving relay RR over the right-hand back contact of the transfer relay TR and through the winding of the break relay BR to the main line. When a negative marking impulse is transmitted from station A, positive and negative battery will be connected to the opposite ends of the main line under these conditions, so that augmented current flows which operates the break relays at both stations. The break relay at station A performs the functions previously described. Break relay BR at station E upon being energized produces no result, as the circuit of the transfer relay TR is held open at the break key BK. As soon as the break key is restored, the apparatus is in condition to transmit signals, and signals may be. transmitted by interrupting the circuit of the pole changer PG through the agency of the transmitting distributor TD- thereby sending positive and'negative signals over the line.

If. while station A is receiving, it is desired to again transmit to station E, the operation of the break key at station A will apply positive battery to the line ML as already described. When a marking impulse is being transmitted from station B, the distributor TD will close the circuit of the pole changer PC to connect the negative side of the generator G to the line ML,

so that augmented current flows over the line operating the break relays at both stations. The break relay at station A produces no effect upon beingenergized, but the break relay BR at station B closes the circuit of the transfer relay TR through the contact of thel-zey BK. The transfer relay TR is accordingly energized and locked up, opei'i-circuiting the break relay BR and connecting the receiving relay RR directly between the main line and ground. The apparatus is new again in condition to receive signals, and signals may be transmitted from station A. to station B.

It will be obvious that the general principles herein disclosed may be embodied in many other organizations widely different from those illustrated without departing from the spirit of the invention as defined in the following claims.

lVhat is claimed is:

1. In a signaling system, a line circuit, terminal stations at each end of said line circuit, transmitting apparatus and receiving apparatus at each terminal station, a. local subscribers loop extending from one of said terminal stations to a subscriber station, telegraph apparatus at the subscriber station whereby the transmitting apparatus at the corresponding terminal station may be controlled from the subscriber station over the loop and whereby the telegraph apparatus will respond to the receiving apparatus at the terminal station, telegraph apparatus at the other terminal station directly controlled by the transmitting and receiving apparatus thereat, and means whereby during non-signaling condition the transmitting apparatus at one terminal station will be associated with the line, and the receiving apparatus at the other terminal station will be associated with the line for lll'itl'lSl'HlSSlOl] in one direction, and for transmission in the opposite direction the connections will be reversed.

2. In a signaling system, a line circuit, a. terminal station: associated with said line circuit, transmitting apparatus at said terminal station including pole changing contacts, a receiving relay at said terminal station and switching means whereby, under certain conditions said receiving relay may be connected between said line circuit and a return path, and means whereby, under other circumstances, both said receiving relay and said pole changing contact may be included between said line circuit and a return path.

3. In a signaling system, a line circuit, a terminal station associated with said line. circuit, transmitting apparatus at said terminal station including pole changing contacts, a receiving relay at said terminal station, a break relay and a break key at said terminal station and a transfer relay jointly and said ,pole changing contact between said line circuit and a return path.

In testimony whereof, I have signed niy name to this specification this 19th day of November, 1921.

EDWARD F. WATSON 

